The #1 source for news about monkeys and apes

[Carrie McLaren <carrie AT stayfreemagazine.org>]

Mystery Pregnancies Puzzle L.A. Zookeepers
http://abcnews.go.com/sections/science/DailyNews/monkeytrouble990513.html

Yoshi carries her offspring Toshi at the Los Angeles Zoo. (SEE WEBSITE FOR
PHOTO)


By Deborah Hastings
The Associated Press
L O S   A N G E L E S, Calif.

May 13,1999

There's some monkey business going on at the Los Angeles Zoo.

The chimpanzees keep getting pregnant, even though all the males thought
capable of breeding have had vasectomies.

No one is quite sure why it's happening, but it's created the kind of
excitement zoos lust for.

"The zoo has never had this much publicity about anything," zoo keeper
Vicki Bingaman said.

In the past three months, two chimps have given birth and a third is
pregnant. DNA tests to determine the father-or fathers-cannot be done for
months, until the babies are old enough to be separated from their mothers.

The real mystery is this: Three of the four adult males had vasectomies in
1996. And Toto, who is 45, has never shown sexual interest in anyone but
himself. As for 2-year-old Ripley and 4-year-old Glenn, they were
considered too young to breed.

How Could This Happen?

Bingaman thinks the vasectomies may have failed. Vasectomies are known to
have a 1 percent failure rate in humans.

"Chimps are very resilient. It wouldn't surprise me if they found some way
around" their vasectomies, Bingaman said.

Charles Sedgwick, the zoo's director of animal health sciences, thinks
she's wrong.

"Vasectomies in chimps are the same as vasectomies in people, except that
chimps are much more prodigiously endowed," Sedgwick said. In both humans
and chimps, the tubes that carry semen are severed, and "there's not much
chance that would spontaneously reattach."

Sedgwick thinks Toto or perhaps the youngsters are the fathers. He said
there have been rare cases of young chimps impregnating a female.

Too Many Apes
The chimps at the Los Angeles Zoo have sex every day, Sedgwick said. The
zoo started trying to curb its chimp population about eight years ago
because the enclosure was getting too crowded and chimps aren't an
endangered species.

 First, zoo keepers distributed birth control pills. But the females passed
them around. Babies ate them. So did males. Then Bingaman tried
contraceptive implants. They weren't strong enough.

"So we vasectomized the males and we still had babies," she said.

The newest, a four-pound girl, was born last week and brings the chimp
population to 15. The zoo and a radio station are sponsoring a
name-the-chimp contest, to start Sunday.

Back to Birth Control Pills
Bingaman thinks the problem is finally under control. A new, more
naturalistic enclosure gives zoo keepers more room to walk around and make
sure only the adult females are swallowing birth control pills.

On Thursday, Susan Taj, a parent volunteer, helped lead a group of
second-graders on a field trip. She had heard about the chimp hanky-panky
and called it unbelievable. Would she explain it to the children?

"Not to second-graders, I don't think," she said.